Need help with circuit diagram

Discussion in 'The Projects Forum' started by noble, Jun 6, 2007.

  1. noble

    Thread Starter New Member

    Jun 4, 2007
    3
    0
    Hi every one

    am studying electronics and I want to make an electronic billboard displying using LEDs just by using counters, registers and flip flops.I need a working circuit diagram to connect my components.

    thank you
     
  2. Papabravo

    Expert

    Feb 24, 2006
    10,149
    1,791
    Do you mean individual LEDs or do you mean 7/14/16 segment LEDs. How many of each in either case?
     
  3. noble

    Thread Starter New Member

    Jun 4, 2007
    3
    0
    Hi Papa Bravo,
    thanks for responding. Am sorry for not putting all the details. I meant individual LEDs and they will be 150 of them (50 green, 50 red, 50 yellow)
    bye for now
     
  4. Papabravo

    Expert

    Feb 24, 2006
    10,149
    1,791
    How will these 150 LEDs be arranged?
    The reason I ask is that you will need to think about how you intend to generate characters on a grid of LEDs. I hate to burst your bubble, but I don't think that counters, registers and flip-flops are going to be much help in this application.

    Take a look at the following datsheet from Maxim
    http://datasheets.maxim-ic.com/en/ds/MAX6954.pdf
     
  5. mozikluv

    AAC Fanatic!

    Jan 22, 2004
    1,437
    1
    we're still blind as to what you intend to display. what components do you intend to connect. pls provide some more info.:confused:

    moz
     
  6. noble

    Thread Starter New Member

    Jun 4, 2007
    3
    0
    Hi
    I need them to display three letters (S O T).and the letters should light in sequence (one after the other i.e S....10seconds O.......10s T.....10s) so the sequence repeats its self.

    I have attached a block diagram I drew up
     
  7. recca02

    Senior Member

    Apr 2, 2007
    1,211
    0
    i think
    a mod 3 counter with a clock pulse of a period of 10 sec might work.
     
  8. cutemanuel

    New Member

    Jul 10, 2007
    3
    0
    Hi Everyone,
    i noticed that Noble have asked the same question i intended to. But the twister is that, is there any way i could save the information that is to be displayed in a flash drive so that instead of bringing down the billboard to edit, i can just do that on the flash and plug it back to run. Pls i need Ideas.

    Best regards
     
  9. recca02

    Senior Member

    Apr 2, 2007
    1,211
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    i think the same can be done with the help of micro controllers no simple changes in programming will change the display patterns.i havent worked with them others on this forum will be able to help.
     
  10. cutemanuel

    New Member

    Jul 10, 2007
    3
    0
    Thanks for the response...i still need more information on how to build this Electronic Billboard. Probably a circuit diagram will be an added plus!!

    Anyone could please assist!

    Best regards
     
  11. JohnnyD

    Well-Known Member

    Aug 29, 2006
    79
    0
    It sounds like you want your homework done for you. I apologise if I am wrong but it isn't very convincing when you just straight-up ask for a circuit diagram without putting forward any thoughts/ideas of your own.
     
  12. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    First, you should decide upon how you are going to represent your characters.

    The least number of "dots" to represent the letters S, O, and T would be a 3x5 grid, like this:
    ooo
    ooo
    ooo
    ooo
    ooo
    Examples:
    ooo
    ooo
    ooo
    ooo
    ooo

    ooo
    ooo
    ooo
    ooo
    ooo

    ooo
    ooo
    ooo
    ooo
    ooo
    ooo

    Typically, an alphanumeric display would represent characters in a 5x7 grid, but your stated requirements make that unnecessary.

    So, you will need 15 LED's to display a single character.
    For readability's sake, you will need to leave a blank column between characters; the blank row is another five.

    Instead of using 50 red, 50 yellow, and 50 green LED's, consider using 50 red/green/yellow LED's, as this will simplify your wiring and mounting considerably, along with making interesting effects possible.

    LED driver IC's: consider using ULN2803's. These are reasonably priced, TTL compatible, compact, and contain 8 Darlington pair NPN transistors. ULN2003's are similar, but contain 7 Darlingtons instead. ULN2x04's are CMOS compatible, but so are the ULN2x03's if you add a 6.8k resistor to each control input, whereas the ULN2x04's can't be (practically) used with TTL. You'll probably want to re-use these drivers for another project later. Keep flexibility in mind.

    Shift registers: you'll need serial-in, parallel-out universal shift registers. One n-bit shift register will drive n LED's on one row, via the ULN2x03's.

    I'm not trying to do this whole project for you; just giving you some ideas.
     
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